Non-polar surface GaN epitaxial wafer and preparation method of non-polar surface GaN epitaxial wafer

Abstract

The invention discloses a non-polar surface GaN epitaxial wafer. A non-polar GaN film is synthesized and grown on a sapphire substrate by using a metal organic chemical vapor deposition (MOCVD) system, and the film comprises a low-temperature buffer layer grown on the sapphire at one time and an alpha surface GaN film. Different epitaxial structures of light emitting diodes, laser devices, solar cells and the like are grown on the film in different periods. The growth of the non-polar alpha surface GaN material can be effectively controlled, and the quantum efficiency and the luminous efficiency in the periods can be improved.

Description

technical field [0001] The invention relates to the field of semiconductor material preparation, in particular to a non-polar surface GaN epitaxial wafer and a preparation method thereof. Background technique [0002] At present, the mainstream substrate for the epitaxial growth of GaN thin films in business is c-plane sapphire crystal. Usually, GaN thin films grown on c-plane sapphire substrates are grown along the direction of its polarity axis, that is, the c-axis, and the thin films have spontaneous polarization and compression. The electric polarization effect leads to a strong built-in electric field inside the film, which greatly reduces the luminous efficiency of the GaN film. In addition, the polarization electric field also brings a serious problem: with the increase of the injection current, the luminous peak of the diode will also undergo a large blue shift. [0003] One of the solutions is to grow cubic nitride heterojunctions. Theory shows that there is no sp...

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Problems solved by technology

[0002] At present, the mainstream substrate for the epitaxial growth of GaN thin films in business is c-plane sapphire crystal. Usually, GaN thin films grown on c-plane sapphire substrates are grown along the direction of its polarity axis, that is, the c-axis, and the thin films have spontaneous polarization and compression. The electric polarization effect causes a strong built-in electric field inside the film, which greatly reduces the luminous efficiency of the GaN film

In addition, the polarized electric field also brings a serious problem: as the injection current increases, the peak of the diode's light emission will also undergo a large blue shift.

Although the lattice mismatch and thermal mismatch between sapphire and GaN are relatively large, with the continuous improvement and improvement of sapphire substrate processing technology and GaN epitaxial growth process, the process of epitaxial GaN thin film on sapphire substrate is becoming more and more mature. Commercialization. Craven et al. first reported the growth of non-polar GaN films on r(0112) plane sapphire. Due to the large lattice mismatch, the quality of the grown films was poor and there were many defects (mainly dislocations and stacking faults).

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